Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
ARAUJO, Fabio Fernando de; GUABERTO, Luciana Machado and SILVA, Iassanã Francisco da. Bioprospection of plant growth promoter rhizobacteria in Brachiaria brizantha . R. Bras. Zootec. [online]. 2012, vol.41, n.3, pp. 521-527. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982012000300007.
This study proposed to select and characterize bacteria of the genus Bacillus on rhizosphere of Brachiaria brizantha as plant growth promoters and to correlate the different selection criteria of the bacteria utilized in laboratories and greenhouse. After collecting samples of plants in three municipalities of Sao Paulo, bacteria were isolated from the rhizosphere and subsequent phenotypic characterization was carried out, regarding the potential for colonization of the roots of pasture, antagonism to pathogenic fungi, production of auxins, phosphatases and proteases in addition to the genotypic characterization using PCR-RAPD. As final evaluation of Bacillus sp. isolates, a greenhouse experiment was performed with seed inoculation and cultivation of Brachiaria brizantha with three harvests, during 180 days. The experiment was distributed in completely randomized design with four replications. Of the 45 isolates of Bacillus sp. evaluated, seven were able to root colonization and three (1A, 2B and 6A) were able to promote the growth of Brachiaria brizantha, on the average of three harvests. The evaluation of auxin and phosphatase production was important in the selection protocol of Bacillus sp. to promote plant growth. Protease production was detected in all isolates, but there was no correlation of this characteristic with plant growth.
Keywords : Bacillus sp.; enzymatic activity; pastures; rhizosphere.